This interesting bug in many calculators has circled the web millions of times in the last few years (a recent example ). Looks like Bing is on the right track in this department anyway… Unless of course they spent more time and effort working on preventing all of Google’s little flaws instead of working on higher quality results, but that really remains to be seen.
bingcansubtract0 Bing can subtract, Google still cannot.

The paranoid part of me thinks that specific effort was placed on fixing this bug in hopes of getting some mass diggs in favor of their new search engine. Who knows… The fact that a 30 digit number will give incorrect results gives a little more credit to my left brain…